Perhaps you should try some spelling variations:
van cham » van chat, van tham, va cham
hieu van » hieu va, thien van, lieu va
dau tren » dau tien, dat tren, dau tieng
nang doc » nang luc
doc hoc » duoc hoc, toc hoc, duc hoc
sach ky » sac ky, sach y, sach ty
hanh va » hang va, hanh vi
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va
va dau » va dao

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (cac ky)) nang doc hoc. hieu van cham ((xuc va) or (luc va)) hanh va dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (cac ky)) nang doc hoc. hieu van cham ((xuc va) OR (luc va)) hanh va dau tren.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (cac ky)) nang doc hoc. hieu van cham ((xuc va) or (luc va)) hanh va dau tren*.